Feed control means for refrigerating apparatus



April 3, 1956 R. w. KRITZER 2,740,263

FEED CONTROL MEANS FOR REFRIGERATING APPARATUS Filed April 6, 1953 FEEDCONTROL MEANS FOR REFRKGERATKNG APPARATUS Richard W. Kritzer, Chicago,Ill.

Application April 6, 1953, Serial No. 347,033

8 Claims. (Cl. 62-3) The invention relates to apparatus of thecapillary-tube type for feeding condensed refrigerant from refrigeratingapparatus to an evaporator or cooling unit.

One object of the invention is to provide capillary-tube type ofrefrigerant feed means which is controlled by the temperature of therefrigerant of which has passed through the evaporator or cooling unitand which varies responsively to variations in the evaporation of thecondensed refrigerant in the evaporator or cooling unit.

Another object of the invention is to provide simple and efficient meansof the capillary-tube type for feeding refrigerant to the cooling. unit.

Another object of the invention is to provide improved means of thecapillary type for feeding refrigerant to an evaporator or cooling unit.

Other objects will appear from the detail description.

The invention consists in the several novel features hereinafter setforth and more particularly defined at the conclusion hereof.

In the drawings:

Fig. 1 is an elevation of feed-means for the refrigerant embodying theinvention, being shown in normal operation with a full load on theevaporator, the compressor and condenser being diagrammatically shown ona smaller scale.

Fig. 2 is a similar view showing the feed-means for the refrigerant,operating to cut-off the feed to the evaporator, when the refrigerant isnot being evaporated in the evaporator.

Fig. 3 is a section taken on line 33 of Fig. 1.

The invention is exemplified in apparatus or means for feeding condensedrefrigerant from a refrigerating apparatus which comprises amotor-driven compressor A for the refrigerant, a condenser B for therefrigerant, and an evaporator or cooling unit in which the refrigerantabsorbs heat and is evaporated before it is passed into the suction lineto the compressor. The compressor and condenser may be of any suitableconstruction and operate as well understood in the art.

The invention is exemplified with an evaporator or cooling unit,generally designated 10, which includes a series of paralleltube-sections, serially connected by loops to form a coil 12. A seriesof fins 13 are provided on the coil for heat radiation.

An inlet 14 for the refrigerant is communicatively connected totube-section 11 at the inlet end of the coil 12. The outlet end of coil12 is communicatively connected by a line 18 to the suction side of thecompressor.

A capillary tube generally designated 20 is communicatively connectedWith the condenser B for feeding, at a limited rate, refrigerant fromthe condenser, into a columnar receptacle 24 from which the refrigerantpasses through the inlet tube 14, into the first section of the coil 12for evaporation, by the absorption of heat. The capillary tube 20includes a loop 21 which is mounted in contact or heat exchange relationwith the fins 13, and extends along the inlet tube-section 11 of thecoil 12, for rendering the loop 21 thermally responsive to the tem-.nited Sttes Patent T 2,740,263 Patented Apr. 3, 1956 perature changesin said section of the coil 12. The loop 22 of tube 20 is connected by abend 22 to a downwardly directed discharge terminal 23 for feedingrefrigerant into receptacle 24. These temperature changes result fromvariations in the evaporation of the refrigerant in the inlet coil 11 ofevaporator 12 which vary the density of the refrigerant in loop 21. Whenliquid refrigerant flowing through loop 11 of the evaporator has notbeen changed to gas, the loop 21 of the capillary tube is cooled by itscontact with the fins 1 3 and liquid refrigerant will flow through loop21, bend 22 and terminal 23 into the receptacle 24. When gas is flowingthrough loop 11 of the evaporator, it will heat capillary loop 21 andreduce the flow of usable refrigerant liquid through loop 21. In thismanner, the liquid refrigerant in receptacle 24 will be increased ordecreased responsive to the temperature of the refrigerant in loop 11 ofthe evaporator.

The lower end of receptacle 24 is communicatively connected by a U-tube26 to the lower end of a columnar receptacle 27 which functions as anexpansion-chamber 2S. Receptacle 27 is mounted in heat exchange relationWith the suction-line 18 for expanding and contractingv the gas inchamber 28 responsively to the temperature of the refrigerant flowingthrough line 18 to the compressor. The receptacles 2 4 and 27 contain avolume of liquid refrigerant which is retained in receptacle 24 duringthe normal rate of feed of refrigerant through capillary tube 20, andwhile the hot gas passing through suction line 18 expands the gas inreceptacle 27, as shown in Fig. 1. When there is substantially noevaporation in the coil 12,v and the cold refrigerant passes throughsuction line 18 to the compressor, the gas in chamber 28 in receptacle27 will be condensed for the transfer of liquid refrigerant fromreceptacle 24 to receptacle 27, as shown in Fig. 2. While therefrigerant is being evaporated in coil 12, there will be a pressuredrop in the inlet section of coil 12' which will lower the temperatureof the loop 21 of the capillary tube so that it will remain cool for thenormal flow of refrigerant to the receptacle 24 as shown in Fig. 1.While the refrigerant in the suction line 18 cool-s the gas in thechamber 28, which occurs When there is not enough" heat load toevaporate the refrigerant in the coil 12, the condensed gas in chamber28 will retain the liquid refrigerant in receptacle 27 and out ofreceptacle 24 as shown in Fig. 2. There will be no pressure" drop in theinlet sec tion of loop 11 of coil 12 and an increase of the temperatureof the loop 21 of capillary tube 20, which is in heatexchange relationwith the coil 12. The increase in the temperature of the loop 21 Willreduce the flow of usable refrigerant to the receptacle 24.

The operation is as follows:

Assuming the compressor is operating with a full load on the evaporator,the liquid refrigerant will be disposed in receptacle 24 substantiallyas illustrated in Fig. l. Refrigerant Will be drawn from receptacle 24through pipe 14 into the coil 12 of the evaporator. Heat is absorbed bythe refrigerant in its passage through the coil 12, and the refrigerantwill be evaporated before it reaches the suction-line 18. Theevaporation will reduce the pressure in the coil 12, and will start inthe inlet section of coil 12 and progressively increase until the hotgas is produced before it reaches the suction line 18. This evaporationin the section of the coil 12 adjacent the loop 21 of the capillary tubewill cool and prevent said loop 2! from being heated sufiiciently torestrict the normal flow of refrigerant through loop 21 to the coil 12.The hot gas from the evaporator passing through suction line, 18 to thecompressor will expand the gas in the chamber 28 in the receptacle 27and hold the liquid refrigerant outside of receptacle 27 and in the;receptacle 24. The terminal 23 of the capillary feed-tube will besubmerged, and the suction in the coil 12 will feed the refrigerant fromthe upper end of receptacle 24 through inlet pipe 14 into the coil 12 ofthe evaporator. This condition will continue so long as evaporationoccurs in the inlet section of the coil 12. The capillary tube will feedrefrigerant in proper quantity for cooling the evaporator when it isoperating with a full load until the load is reduced or there is anoverfeed of refrigerant.

When the load on the evaporator decreases, or an excess of refrigerantis fed to the evaporator, the lack of vaporization in the evaporatorwill cause cool refrigerant to flow into the suction line 18. The coolrefrigerant in the suction line will reduce the temperature in theexpansion chamber 28 and condense the gas above the liquid in receptacle2.7. This will draw the liquid from receptacle 24 into receptable 27 asshown in Fig. 2. The terminal 23 of tube 20 will be above the liquidlevel in receptacle 24, and the inlet pipe 14 will be cut off from theliquid in receptacle 24. The refrigerant from terminal 23 will drop tothe bottom of the receptacle 24. There being substantially no flow ofrefrigerant or vaporization in the inlet section of the coil 12, itstemperature will increase and raise the temperature of the loop 21 ofthe capillary tube 20. This increase in temperature will cause the loop21 to restrict the flow of the refrigerant to the receptacle 24.

When the liquid refrigerant has been exhausted by the compressor, fromthe suction line, the temperature of the gas in chamber 28 will increaseand it will expand and force the liquid from receptacle 2'? into thereceptacle 24. The liquid column in receptacle 24 will be raised abovethe terminal 23 of the capillary tube 20, so that the refrigerant can befed from receptacle 24 into the coil 12. When the liquid refrigerant hasbeen drawn from the suction line by the compressor, vaporization willoccur in the inlet section of the coil 12 and the temperature of theloop 21 of the capillary tube 24} will drop so it will feed therefrigerant to receptacle 24 at the normal rate of flow.

In this manner, the feed of the refrigerant to the evaporator iscontrolled and varied responsively to variations of temperature of therefrigerant in the suction line, and the feed of the refrigerant will bereduced when unevaporated refrigerant leaves the evaporator or reachesthe suction-line. When the refrigerant is evaporated in the evaporator,there will be the normal rate of feed of the refrigerant to theevaporator for a full load.

The invention exemplifies a device of the capillarytube type for feedingrefrigerant to an evaporator or cooling unit, which is responsive tothermal variations of the refrigerant in the suction line, for variablycontrolling the delivery of the refrigerant to the evaporator or coolingunit, and for reducing the refrigerant when there is an over-feed or areduction of the load on the evaporator. The device for this purpose issimple in construction and eflicient in operation.

Having thus described the invention what 1 claim as new and desire tosecure by Letters Patent is:

1. In a refrigerating system which includes a compressor and a condenserfor the refrigerant and an evaporator including tubing and a suctionline between the evaporator and the compressor; apparatus for feedingrefrigerant to the evaporator, comprising a capillary tube having aportion thereof in heat exchange relation with the exterior of the inletportion of the evaporator for varying the flow of refrigeranttherethrough responsively to temperature changes in said portion of theevaporator, a columnar receptacle into which the capillary tubedischarges the refrigerant as varied by said temperature changes in theevaporator, a conduit for refrigerant from the upper portion of thereceptacle to the inlet of the evaporator, and means controlled byvariations of temperature of the refrigerant from the evaporator forcontrolling the rate of flow of refrigerant from the receptacle to theevaporator.

2. In a mechanical refrigeration system which includes, a compressor anda condenser for the refrigerant and an evaporator or cooling unitconnected to return refrigerant to the compressor; apparatus for feedingrefrigerant to the evaporator, comprising: a capillary tube connected toreceive refrigerant from the condenser, a receptacle into which therefrigerant is delivered from the capillary tube, and which is connectedfor feeding the refrigerant into the evaporator, and means controlled bythe temperature of the refrigerant from the outlet of evaporator, forcontrolling the feed of the refrigerant from the receptacle to theevaporator, said capillary tube being in heat transfer relation with theinlet portion of the evaporator, for restricting the flow to thereceptacle when the refrigerant is not evaporating in the evaporator.

3. in a mechanical refrigeration system which includes, a compressor anda condenser for the refrigerant, and an evaporator or cooling unitconnected by a suction-line to return refrigerant to the compressor;apparatus for feeding refrigerant to the evaporator, comprising acapillary tube connected to receive refrigerant from the condenser andin heat transfer relation with the inlet portion of the evaporator forvarying the flow responsive to variations in evaporation in theevaporator, a connection for feeding refrigerant from the capillary tubeto the evaporator, and a receptacle provided with an expansion chamber,and in heat transfer relation with the suction line, for actuating acolumn of refrigerant to cut off the flow of refrigerant to saidconnection responsive to the decrease of the temperature in the suctionline, and for actuating the column of liquid for the fiow of refrigerantto the evaporator when the temperature in the suction line is increased.I

4. In a mechanical refrigeration system which includes, a compressor anda condenser for a refrigerant, and an evaporator or cooling unitconnected by a suction line to return refrigerant to the compressor;apparatus for feeding refrigerant into the evaporator, comprising: acapillary tube connected to receive refrigerant from the condenser, acolumnar receptacle into which the capillary tube discharges therefrigerant, a connection for feeding refrigerant from the top of thereceptacle into the evaporator, the capillary tube being in heattransfer relationwith the inlet portion of the evaporator for varyingthe fiow' of refrigerant to the receptacle responsive to variations inthe temperature in the inlet portion of the evaporator and means forraising and lowering a column of refrigerant in the receptacle,responsive to variations in the temperature of the refrigerant in thesuction line for controlling the feed of the refrigerant into theevaporator.

5. In a mechanical refrigeration system which includes,

a compressor and a condenser for a refrigerant, and an evaporator orcooling unit connected by a suction line to return refrigerant to thecompressor; apparatus for feeding refrigerant into the evaporator,comprising; a capillary tube connected to receive refrigerant from thecondenser, a columnar recptacle into which the capillary tube dischargesthe refrigerant, a connection for feeding refrigerant from the top ofreceptacle into the evaporator,

and means for raising and lowering a column of refrigerant in thereceptacle, responsive to variations in a the temperature of therefrigerant in the suction line,' for controlling the feed of therefrigerant into the evaporator,

the capillary tube being in heat exchange relation with the evaporatorfor restricting the flow to the receptacle when the feed to theevaporator is cut off.

6. In a mechanical refrigeration system which includes, 1

a compressor and a condenser for the refrigerant, and an evaporator orcooling unit connected to return refrigerant to a suction line for thecompressor; apparatus .for feeding refrigerant to the evaporator,comprising: a capillary tube connected to receive refrigerant from thecon denser, a receptacle provided with a feed-chamber into which therefrigerant is deliveredby the capillary tube and connected for the flowof refrigerant into the evaporator, and a second receptacle providedwith an expansion chamber comrnunicatively connected to thefeed-chamber, and in heat transfer relation with the suction line, forcontrolling the flow between said chambers and the feed of therefrigerant to the evaporator the capillary tube being in heat transferrelation with the evaporator for varying the flow of refrigerant intothe feed chamber responsive to the temperature of the refrigerant in theinlet portion of the evaporator.

7. In a mechanical refrigeration system which includes, a compressor anda condenser for the refrigerant, and an evaporator or cooling unitconnected to return refrigerant to a suction line for the compressor;apparatus for feeding refrigerant to the evaporator, comprising: acapillary tube connected to receive refrigerant from the condenser, acolumnar receptacle provided with a feedcharnber into which therefrigerant is delivered by the capillary tube and connected for theflow of refrigerant into the evaporator, and a second columnarreceptacle provided with an expansion chamber communicatively connectedto the feed-chamber, and in heat transfer relation with the suctionline, for controlling the flow between said chambers and the feed of therefrigerant to the evaporator the capillary tube being in heat transferrelation with the evaporator for varying the flow of refrigerant intothe feed chamber responsive to the temperature of the refrigerant in theinlet portion of the evaporator.

8. In a mechanical refrigeration system which includes a compressor anda condenser for the refrigerant, and an evaporator or cooling unitconnected to return refrigerant to a suction line for the compressor;apparatus for feeding refrigerant to the evaporator, comprising: acapillary tube connected to receive refrigerant from the condenser andincluding a section in heat transfer relation with the inlet portion ofthe evaporator, a receptacle provided with a feed-chamber into which therefrigerant is delivered by the capillary tube and connected for theflow of refrigerant into the evaporator, a second receptacle providedwith an expansion chamber communicatively connected to the feed-chamber,and in heat transfer relation with the suction line, for controlling theflow between said chambers and the feed of the refrigerant to theevaporator.

References Cited in the file of this patent UNITED STATES PATENTS2,183,346 Buchanan Dec. 12, 1939 2,359,595 Urban Oct. 3, 1944 2,472,729Sidell June 7, 1949 2,518,587 Zearfoss Aug. 15, 1950 2,520,045 McGrathAug. 22, 1950

